(Reuters) - Shire is to take a leaf out of AstraZeneca's playbook by giving long-range forecasts for its drugs as it seeks to convince shareholders that AbbVie's $46 billion offer undervalues the business.

Flemming Ornskov, Shire’s chief executive, will update investors on prospects for key medicines on Monday afternoon, mirroring the approach of disclosing long-range internal forecasts used by fellow London-listed drugmaker AstraZeneca in its successful defence against Pfizer.